s NOTES. XXXI 



Bd. xix. S. 357 391; and in the Voyage aux Regions e'quinox. t. iii. p. 616 

 and 625. 



( 139 ) p. 119. Hansteen, iiber jahrliche Veranderung der Inclination, in Pog- 

 gend. Ann. Bd. xxi. S. 403429. Compare also, on the influence of the 

 movement of the nodes of the magnetic equator, Sir David Brewster, Treatise on 

 Magnetism, p. 247. Now that, through the abundance of observations at fixed 

 stations, we have so vast a field for special inquiries, we find fresh and fresh 

 complications arise in our search after regularity and law. 

 ( ua ) p. 119. Phil. Trans, for 1841, Pt. I. p. 35. 



( H1 ) p. 119. Compare Sawelieff, in the Bulletin physico-mathematiqne de 

 1'Acad. Imp. de St. Pdtersb. t. x. No. 219, with Humboldt, Asie Centr. t. iii. 

 p. 440. 



( 142 ) p. 120. Sabine, Magn. Observ. at the Cape of Good Hope, vol. i. 

 p. Ixv. If we might trust La Caille's dip observations in 1751 (he, indeed, never 

 failed to invert the poles, but his needle did not move sufficiently freely), there 

 would result for the Cape an increase of inclination of 10*08' in eighty-nine 

 years. 



( 143 ) p. 120. Arago, in the Annuaire du Bureau des Long, pour 1825, 

 p. 285288. 



( 144 ) p. 121. I repeat here that all the European dips cited in this part 

 of the text are in the usual graduation of the circle in 360; it is only those 

 observed by me on the American continent, prior to the month of June 1804 

 (Voy. aux Regions equinox, t. iii. p. 615 623), which refer to a centesimal 

 graduation. 



( 145 ) p. 123. The Churprinz Mine at Freiberg in the Saxon Erzgebirge: 

 the subterranean place of observation was on the 7th " Gezeugstreck," in the 

 "Ludwiger Spathgang;" 80 "Lachter" east of the " Treibschacht," 40 

 "Lachter" west of the "Kunstscbacht;" depth 133^ "Lachter." The obser- 

 vations were made with Freiesleben and Reich, at 2^ h P.M. (temperature of the 

 mine 15-6 Cent.); inclination with needle A 67 37''4; needle B 67 32''7; 

 mean of the two i.eedles in the mine 67 35''05. In the open air, at the surface 

 of the ground, at a spot precisely vertical above the subterranean one, at 11 AJSI., 

 needle A gave 67 33''87, and needle B 67 32'-12; mean of the two needles 

 at the upper station 67 32''99 (temperature of the air 15'8 Cent.). Difference 

 between the results at the upper and lower stations 2'-06. Needle A, which, 

 being the stronger, was always regarded by me with most confidence, gave the 

 difference even higher than the mean of the two, being 3 /- 53 in favour of the 

 lower station ; the difference shown by needle B, taken alone, being scarcely 

 sensible. (Humboldt, in Poggend. Ann. Bd. xv. S. 326.) The method which I 



